What I think is interesting is that suddenly people are throwing out games that are +10 years old and calling them perfect. But we have better graphics now! And better processors! Online play! Why are games that were 2D platformers suddenly perfect?
Let me throw a bit of "Educational" terminology out at you for something to gnaw on. Teachers who assign papers have to grade papers, and grade them fairly. It's not the same as math, wherein a problem is either right or wrong. They create something called a "rubric." (ROO-brick) A rubric is a grading scale that tells you exactly what you have to do to achieve a target score. Generally, there are a max of about five levels of proficiency (imagine that...) and a general minimum of three (something like: "good," "average," "poor"). If you meet all the criteria listed under the maximum score possibility, then you get an A or "good." What a game reviewer theoretically does is subject the game to be reviewed to the rubric that has been created for the purpose of rating it.
The inherent difficulty in this is that when games are designed, the designers don't have the rubric in front of them, like a teacher would do for the class, so the designer doesn't know what the game will be subjected to when it's time for the game to be reviewed. On top of that, a teacher generally has a very specific rubric for each project or paper that is being graded. English and Science papers wouldn't (insert: "should NEVER") have the same rubric because the different subjects have different objectives. Different games shouldn't be subjected to the same rubric because different games have different objectives (aside from FUN).
While this would be a great deal more fair, this would also be a great deal more work: each genre of game should have its own rubric to be graded on. (And then, there are always games that don't really fit much of anywhere.) Would you want FFT to be subjected to the same criteria that CoD4 would be? Donkey Konga and Eternal Darkness? Starcraft and Hello Kitty Online? I think I've made that point.
If you equate perfection with 100% in a game, then since nothing is truly perfect then, no, it will never deserve a 100% score.
If you equate 100% with "met the maximum standards" then it's likely by now that plenty of games deserve that rating.
But is it your definition that determines the outcome? Why doesn't someone ask the reviwers what their definitions are, so that everyone will be on the same page. The problem to me here is that no one has asked the reviewers to show us their rubrics. We're just seeing the final scores. It's what they are rating the games by that matter.
If the reviewers don't think that 10/10 means a game is the second coming of Jesus, they why should we interpret it that way?